Sam Bottoms, who started his acting career as a teenager in “The Last Picture Show” and played surfer Lance Johnson in “Apocalypse Now,” died Tuesday in Los Angeles of brain cancer. He was 53.

He was the brother of actors Timothy, Joseph and Ben Bottoms and the husband of producer Laura Bickford.

Bottoms was cast as a mentally handicapped young man in “The Last Picture Show” when director Peter Bogdanovich spotted him on the street while he was visiting his brother Timothy on the Texas film set.

In 1976, he was cast in “Apocalypse Now” at the age of 20, as one of the young sailors who went upriver with Martin Sheen’s Captain Benjamin Willard to meet up with Marlon Brando’s Colonel Kurtz.

In one memorable scene, Bottoms’ character is ordered to surf in the middle of a war zone by the surf-obsessed lieutenant colonel played by Robert Duvall. “He, Larry Fishburne and Fred Forrest were like a young family almost to me, and they went through thick and thin uncomplainingly,” Coppola told the L.A. Times about the year and a half-long Philippines shoot.

Coppola later cast him in his 1987 Vietnam film “Gardens of Stone.”

Bottoms appeared in features including Clint Eastwood’s “The Outlaw Josey Wales” and “Bronco Billy” and more recently in “Seabiscuit,” “Shopgirl” and “SherryBaby.”

On television, he appeared on series including “NYPD Blue,” “The X Files,” “Murder, She Wrote,” “Marcus Welby” and “Lucas Tanner.” He played Cal Trask in mini-series “East of Eden,” which also starred his brother Timothy.

Born in Santa Barbara, Calif., he began acting in local theater at the age of 10,

In addition to his wife, he is survived by two daughters; brothers Timothy, Joseph and Ben; his father and his mother.

Donations may be made to Angels Among Us, Preston Robert Tisch Brain Tumor Center, Duke University, DUMC Box 3624, Durham, N.C., 27710.